The present invention relates to wastewater treatment systems and in particular to a covered lagoon based wastewater treatment system. A lagoon is any earthen basin for containing a body of water.
Conventional lagoon based wastewater treatment systems rely on open air lagoons to permit aerobic and anaerobic treatment of wastewater. A lagoon is any earthen basin for containing a body of water, such as a treatment reactor cell. Lagoon based systems require a large amount of space, on the order of several acres. Once the treatment capacity for a lagoon based system is reached, additional capacity can only be accomplished by building additional lagoons, which requires a significant capital expenditure and the use of more land. In addition, traditional lagoon based systems cannot achieve more stringent effluent limits required by recent environmental regulation changes without further increasing the treatment time or without adding costly mechanical adaptations. Neither of these options are desirable.
Traditional lagoon based systems have several shortcomings. Open air ponds produce odors and permit algae growth which inhibits wastewater treatment. In addition, open air ponds expose the treatment pond to ambient air conditions. In cold climates, this exposure significantly slows treatment and reduces the effectiveness of the treatment since biological activity of the bacteria are decreased. In particular, bacteria which remove ammonia nitrogen are significantly inhibited.
Finally, traditional lagoon based systems produce sludge that settles in all the basins requiring periodic shutdown of the treatment ponds to remove the sludge.